Method of and apparatus for removing parts of a refrigerating system



g- 9, 1966 J. L M. HOLMAN ETAL 3,264,335

METHOD OF AND APPARATUS FOR REMOVING PARTS OF A REFRIGERATING SYSTEM Filed Aug. 21, .1964

FIG.)

0 000 O OOOOO O O OO FIG.2

INVENTORS JOHN L MONTE .HOLMA BY JAMES M. PORTE United States Patent 3,264,835 METHOD UP AND APPARATUS FUR REMOVING PARTS OF A REFRIGERATHNG SYSTEM John L M. Holman, Medary Township, La Crosse County,

and James M. Porter, La (Irosse', Wis, assignors to The Trane (Iompany, La Crosse, Wis, a corporation of Wisconsin Filed Aug. 21, 1964, Ser. No. 391,163 119 filaims. (Cl. 62-401) This invention relates to refrigerating systems and more particularly to a method and apparatus which permits removal of fluid containing par-ts of the system without removing the fluids from the system.

In refrigerating systems, pumps are often mounted below a large reservoir of liquid refrigerant or liquid solution. It has been common practice to remove the refrigerant or the solution or both the refrigerant and solution when a pump must be removed for service.

In order to avoid the necessity of removing the refrigerant or solution, it has been common to provide valves on the suction conduit to the pump and on the discharge conduit from the pump. These valves are closed before removing a pump in order to contain the refrigerant or solution within the system. Such valves are large and consequently expensive. Furthermore they introduce a pressure drop or resistance to flow which is undesirable especially when the liquid pumped is close to its boiling temperature which is often the case.

The instant invention provides the method and apparatus for removing pumps, pump motors and parts thereof from absorption refrigeration machines operated at subatmospheric pressure without the necessity of draining the machine before removal of such parts. This is accomplished in the instant invention by providing a liquid trap between the part to be removed and the machine elements containing large liquid volumes such as the absorber or evaporator. Suflicient inert gas is then introduced into the machine to raise the pressure at the liquid trap to atmospheric pressure whereupon the pump, pump motor or part thereof may be removed without su. stantial loss of liquid from the machine.

The instant invent-ion further contemplates the simultaneous removal of such pump and motor parts from two liquid circuits such as absorbent solution circuit and refrigerant circuit which contain liquids of different densities. This aspect of the invention is similar to that described in the paragraph above, however, additional means is provided to allow liquid to flow between the circuits thereby balancing the circuits despite the difference in densities of the different liquids thereby permitting simultaneous removal of parts from both circuits.

It therefore is an object of this invention to provide apparatus for and a method of removing fluid containing parts of a refrigerating system such as pumps without removing the fluids from the system.

It is another object of the invention to provide a valve on a part to be removed in order that the valve may be opened to allow a gas or air to replace the fluid at the part to be removed.

It is another object of the invention to provide a sight glass on the suction conduit to a pump for the purpose of determining the level of liquid in the suction conduit.

It is another object of the invention to provide means for the flow of liquid between the liquid refrigerant circuit and the liquid absorbent circuit of an absorption refrigeration machine to permit the removal of both refrigerant and absorbent pumps without draining the liquids therefrom.

Other objects and advantages of the invention will become apparent as this specification proceeds to describe 3,264,835 Patented August 9, 1966 ice the invention with reference to the accompanying drawing in which:

FIGURE 1 is a schematic illustration of an absorption refrigeration system in which the pump and/or pump motors may be removed without draining the system; and

FIGURE 2 is an enlarged view of a pump unit shown in FIGURE 1 with a portion broken away to show the interior thereof.

Referring now to the drawings, the absorption refrigeration system shown is of the type having a single shell lit with a partition 12 separating a high pressure chamber containing a generator 14 and a con-denser 16 from a low pressure chamber containing an evaporator 18 and an absorber 24 It should be understood that other arrangements might be used; for instance, the generator and the condenser might be in one shell and the absorber and evaporator might be in a second shell with conduits therebetween for conducting fluids.

Various combinations of refrigerant and absorbent may be used. A solution of lithium bromide and water has been found highly satisfactory as the absorbent for use with water as the refrigerant.

The generator 14 has a coil 22 supplied with a heating fluid such as steam from a source (not shown). The coil 22 heats the absorbent solution in the generator causing it to boil and force refrigerant vapor into the condenser 16 via passage 24. The concentrated absorbent solution may be returned to the absorber 20 by suitable means (not shown).

Condenser 16 has a coil 26 supplied with a cooling fluid from a source (not shown) for condensing refrigerant vapor. The refrigerant condensate flows through an opening 23 into the evaporator 18.

Evaporator 18 has a coil 30. Fluid from a refrigerating load such as an air conditioning system is circulated through the coil 30 where it is reduced in temperature and returns to the refrigerating load. The coil 30 is cooled by the evaporation of liquid refrigerant. The refrigerant vapor from the evaporator passes freely to the absorber 2t where it is absorbed by the absorbent solution therein.

Absorber 20 has a cooling coil 32 supplied with a cooling fluid from a source (not shown). In the operation of the absorption refrigeration machine, a portion of the absorbent solution with absorbed refrigerant is pumped from the absorber to the generator by any appropriate pump and conduit means (not shown) where it is again concentrated.

It will be understood that during normal operation of the device as a refrigeration machine the low pressure chamber of shell it) is maintained at a pressure equivalent to the vapor pressure of the refrigerant therein. Initial and subsequent evacuation of air and other noncondensables from the absorption system may be made by a vacuum pump 34 connected to the system via shut-off valve 36.

When water is used as a refrigerant, the pressure may be about .12 p.s.i.a.

The liquid refrigerant which is not vaporized in the evaporator 18 by coil 30 gravitates to the lower portion thereof to an outlet 38 whereupon it is recirculated to the upper portion of the evaporator by the liquid refrigerant circuit 40. The liquid refrigerant circuit has a refrigerant pump 42 disposed below the evaporator, a suction conduit 44 connecting between outlet 38 and the suction inlet of pump 42, and a discharge conduit 46 connected to the discharge outlet of pump 42 for spraying recirculated refrigerant liquid into the upper portion of the evaporator. The suction conduit 44 may include an enlarged tank portion 48 for storage of excess liquid refrigerant. As an alternative to storage tank 48, excess liquid refrigerant may be stored in the lower portion of the evaporator.

At least a portion of the absorbent solution in the bottom of the absorber 20 is recirculated to the upper portion of the absorber by an absorbent solution circuit 50. The absorbent solution circuit includes an absorbent solution pump 52 disposed below the absorber, a suction conduit 54 connecting between the lower portion of absorber 20 and the suction inlet of pump 52, and a discharge conduit 56 connected to the discharge outlet of pump 52 for spraying recirculated absorbent solution into the upper portion of the absorber.

Pumps 42 and 52 may be driven by the same motor means or by separate motor means as shown. Each pump in combination with the motor means therefor will hereinafter be termed a pump unit. Several pump units may therefore include a common motor. For purposes of illustrating the invention, pump units for pumps 42 and 52 may be identical and for this reason only the pump unit incorporating pump 52 is illustrated in FIGURE 2.

Pump 52 is provided with a motor 58 which has a shaft carrying pump impeller 60. It is significant to certain aspects of the present invention that the pum motor is arranged in contact or fluid communication with the fluid in its respective fluid circuit.

In the event that either pump or pump motor need be removed for repair or service, bolted sealing flanges 62 may be provided at the pump inlet and outlet and bolted flange 64 may be provided at the interface between the motor and pump. It will be apparent from the above described structure that removal of the pump or motor from either pump unit requires breaking the seal of the fluid circuit in which it is incorporated.

The present invention contemplates a method and apparatus of breaking the seal to the liquid refrigerant circuit 40 and/or absorbent solution circuit 50 without the necessity of draining the refrigerant storage means and/ or absorber and without requiring valves in the suction and/or discharge conduits associated with the pump unit. To this end, suction conduit 44 is provided with a fluid trap 66 which extends below the inlet of pump 42 and discharge conduit 46 is provided with a fluid trap 68 which extends below the outlet of pump 42. In like manner, suction conduit 54 is provided with a fluid trap 76 extending below the inlet to pump 52 and discharge conduit 56 is provided with a fluid trap 72 extending below the outlet of pump 52. A cross-over conduit '74 having shut-off valve 76 extends between traps 66 and 68. A second cross-over conduit 78 having shut-off valve 80 extends between traps 70 and 72.

In addition means is provided for charging the low pressure chambers of shell with an inert gas, i.e., a gas which will not be deleterious to the apparatus, absorbent solution or refrigerant. Accordingly, shell 10 has connected thereto a conduit 82 having a shut-off valve 84 and fluid coupling means 86 adapted to be connected to a source of inert gas such as nitrogen gas tank 88. Sight glass tubes 90 and 92 with shut-off valves are connected respectively to the suction conduits 44 and 54 to indicate when suflicient nitrogen has been charged to the shell 10. Pumps 42 and 52 have vents 94 and 96 respectively each of which includes a shut-off valve so that air may be selectively admitted to the pump to drop the liquid level therein when the system is properly charged with nitrogen.

So that parts of both pump units may be removed concurrently, the absorption refrigeration system has a crossover conduit 98 with shut-off valve 100 connected to the suction conduits 44 and 54 at about the level of fluid traps 66 and 70.

Removing system parts To remove pump 52, pumps 34, 42 and 52 are shut down and valve 36 is closed to prevent air leakage back into the system through pump 34. Air has been found deleterious to the apparatus in the presence of absorbent solutions such as lithium bromide. The relative liquid levels in the solution and refrigerant circuits will be determined largely by the refrigerating load on the absorption machine at the time of shutdown.

After pumps 34, 42 and 52 are shut down, nitrogen gas is charged to shell 10 from tank 88 by opening valve 84. The nitrogen is allowed to flow into the shell 10 until the sum of the total gas pressure in the low pressure chamber of shell 10 and the hydrostatic pressure, in suction conduit 54 at a level below pump 52 and above trap 70, substantially equals atmospheric pressure. The term hydrostatic pressure as used throughout this specification and subjoined claims is the pressure of the liquid due solely to gravitational forces upon the liquid. The desired hydrostatic pressure is indicated upon opening the valve at sight glass tube 92 by a liquid level below pump 52 and above trap 70 whereupon a liquid seal is established. if too much nitrogen is introduced to shell 10 as indicated by a liquid level in tube 92 about pump 52, it will be necessary to open valve 36 and operate pump 34 until the proper level is again reached. Vent 96 may then be opened to allow the liquid level within pump 52 to fall below the inlet and outlet thereof.

It will be appreciated that while sight glass tube 92 will accurately indicate the liquid level at trap 70 once vent 90 has been opened, it will not indicate the liquid level in trap 72. To eliminate the possibility of spilling even a very small amount of solution from conduit 56, valve in cross-over conduit 78 between traps 70 and 72 may be opened to allow the liquid levels in traps 70 and 72 to equalize.

It will be understood that the steps Olf charging the shell, terminating the charging step, balancing the liquid levels in the several traps and venting the pump may in part be done concurrently. In fact it may be desirable to perrform each step in increments with other steps interposed as the result of each step will be affected by the other steps.

To remove motor 58 alone, it is necessary to lower the liquid level at the pump unit only sufliciently to prevent air from entering the system through the opening to the system made by removing the motor.

Pump 42 or its motor means may be removed from the system in a similar manner using traps 66 and 68, sight glass tube 90, and cross-over conduit 74. However, it will be understood that the nitrogen gas pressure required to establish a seal for the removal of parts from the refrigerant pump unit will not necessarily be the same as required to establish a seal for removal of parts from the absorbent solution pump unit owing to difference in liquid levels and density. For this reason it is not ordinarily possible to remove parts of both pump units concurrently.

To remove parts from both pump units concurrently it is necessary, in addition to the foregoing steps for removing the several pump units independently, to open valve 100 in cross-over 98 to permit the fluid pressure at traps '66 and 70 to equalize. This is effected by the passage of liquid of a first density of one circuit into the liquid of a second density of the other circuit thereby equalizing the pressures at traps 66 and 70 as shown in FIGURE 1. Only one sight glass tube will be necessary in this method. After the low pressure chamber of shell 10 has been charged with nitrogen to sufliciently lower the liquid level in traps 66, 68, 70 and 72, both pump units or parts thereof may be removed.

Upon reinstallation of the pump units or parts thereof, valves 76, 80, 100 and the valves in sight glass tubes and 92 may be closed. It may be necessary to remove the air trapped at the re-installed part so as to prime the pump. This may be accomplished by charging the absorber and evaporator with additional nitrogen thereby forcing the trapped air out of vent 94 and/or vent 96 whereupon the vents are closed. As an alternative method it may be desirable to simply connect vent 94 and/ or vent 96 to a vacuum pump to withdraw the trapped air before closing the vents. Valve 36 is then opened and the system is purged of nitrogen by pump 34.

Although we have described in detail the preferred embodiment of our invention and method of operating same, it is contemplated that changes may be made without departing from the scope or spirit of our invention and we desire to be limited only by the claims.

We claim:

1. A method of removing a pump motor from an absorption refrigeration system of the character having a closed vessel normally maintained at subatmospheric pressure and normally partially filled with a liquid, a fluid circuit means for conducting liquid from a portion of the vessel to a higher portion of the vessel, a pump disposed in the fluid circuit means at a level below the vessel, and a motor drivingly coupled to the pump and having at least a portion thereof in fluid communication with the liquid in the fluid circuit means, comprising the steps of: providing said fluid circuit means with a liquid trap means disposed below said vessel; providing said vessel with a source of inert gas; charging said vessel with sufficient gas from said source that the sum of the total gas pressure within said vessel and the hydrostatic pressure, in said fluid circuit means at a level below said vessel above said trap, substantially equals atmospheric pressure; and disconnecting and removing said portion of said motor from said refrigeration system.

2. The method as defined by claim 1 wherein prior to the step of disconnecting said portion of said pump motor, said pump is vented to the atmosphere to permit the liquid level therein to fall below the inlet of said pump.

3. A method of removing a pump motor from an absorption refrigeration system of the character having a closed vessel normally maintained at subatmospheric pressure and normally partially filled with a liquid, a pump tfior pumping liquid from the vessel having an inlet and an outlet and disposed below the vessel, a suction conduit communicating with the liquid in the vessel and extending downwardly to the pump inlet, a liquid trap disposed below the pump inlet in the suction conduit, and a motor 'drivingly coupled to the pump and having at least a portion thereof in fluid communication with the liquid circulated by the pump comprising the steps: providing said vessel with a source of inert gas; charging said vessel with sufficient gas from said source that the sum of the total gas pressure within said vessel and the hydrostatic pressure, in said conduit at a level below the inlet of said pump and above said trap, substantially equals. atmospheric pressure; and disconnecting and removing said portion of said motor from said refrigeration system.

4. The method as defined by claim 3 wherein prior to the step of disconnecting said portion of said pump motor, said pump is vented to the atmosphere to permit the liquid level therein to fall below the pump inlet.

5. A method of removing a pump from an absorption refrigeration system of the character having a closed vessel normally maintained at subatmospheric pressure and normally partially filled with a liquid, a pump for pumping liquid from the vessel having an inlet and an outlet and disposed below the vessel, a suction conduit communicating with the liquid in the vessel and extending downwardly to the pump inlet, and a liquid trap disposed below the vessel upstream of the pump inlet in the suction conduit, comprising the steps of: providing said vessel with a source of inert gas; charging said vessel with sufficient gas from said source that the sum of the total gas pressure within said vessel and the hydrostatic pressure, in said suction conduit at a level below the vessel upstream of the inlet of said pump and above said liquid trap, substantially equals atmospheric pressure; and disconnecting and removing at least a portion or" said pump from said refrigeration system.

6. The method as defined by claim 5 where-in prior to the step of disconnecting said portion of said pump, said pump is vented to the atmosphere to permit the liquid therein to fall below the pump inlet.

7. A method of removing .an absorbent solution pump motor from an absorption refrigeration machine of the character having an absorber normally maintained at subatmospheric pressure and normally partially filled with an absorbent solution, an absorbent solution circuit means for conducting absorbent solution from the lower portion of the absorber to the upper portion of the absorber, an absorbent solution pump disposed in the absorbent solution circuit means below the liquid level in the absorber, a motor drivingly coupled to the absorbent solution pump and having at least a portion thereof disposed in fluid communication with the absorbent solution therein, and .a liquid trap in the circuit means below the absorbent solution pump, comprising the steps of: providing said absorber with a source of inert gas; charging said absorber with sufficient gas from said source that the sum of the total gas pressure within the absorber and the hydrostatic pressure, in said circuit means between said pump and said trap, substantially equals atmospheric pressure; and disconnecting and removing said portion of said motor from said absorption refrigerating machine.

8. An absorption refrigeration machine comprising in combination an evaporator, an absorber, fluid passage means connecting the upper portion of said evaporator to the upper portion of said absorber, a refrigerant circuit means for conducting refrigerant from the lower portion of the evaporator to the upper portion of the evaporator, a refrigerant pump disposed in said refrigerant circuit means below said evaporator, an absorbent solution circuit means for conducting absorbent solution from the lower portion of the absorber to the upper portion of the absorber, an absorbent solution pump disposed in said absorbent solution circuit means below said absorber, motor means for driving said refrigerant pump and absorbment solution pump and a liquid trap in one of said circuit means disposed below in series with and upstream of the pump therein.

9. The apparatus as defined by claim 8 wherein means is provided for venting one of said pumps.

10. The apparatus as defined by claim 8 wherein a sight glass is connected to said one circuit means.

11. A method of removing at least a portion of each of several pump units from an absorption refrigeration system of the character having an absorber and evaporator normally maintained at subatmospheric pressure and normally at lea-st partially filled with absorbent and refrigerant liquids having first and second densities respectively, a first fluid circuit connecting the lower portion of the absorber to the upper portion thereof and having a segment extending below the absorber, a first pump unit disposed in the first fluid circuit below the absorber for pumping absorbent liquid from the absorber and having a portion to be removed, a second fluid circuit connecting the lower portion of the evaporator to the upper portion thereof and having a segment extending below the evaporator, a second pump unit disposed in the second fluid circuit below the evaporator for pumping refrigerant liquid from the evaporator and having a portion to be removed, the first and second pump units including motor means for driving the pumps thereof, a first liquid trap disposed in the first fluid circuit below the absorber upstream of that portion of the first pump unit to be removed, and a second liquid trap disposed in the second fluid circuit below the evaporator upstream of that .portion of the second pump unit to be removed, comprising the steps of: providing said absorber and evaporator with a source of inert gas; charging said absorber and evaporator with sufficient gas from said source that the sum of the total gas pressure within said absorber and the hydrostatic pressure, in said first fluid circuit at a level below the absorber upstream of that portion of said first pump unit to be removed and above said first trap, substantially equals atmospheric pressure and passing sufficient quantity of liquid of one density from one of said first and second fluid circuits into the liquid of the other density in the other of said first and second fl-uid circuits that the sum of the total gas pressure within said evaporator and the hydrostatic pressure, in said second fluid circuit at a level below the evaporator upstream of that portion of said second pump unit to be removed and above said second trap, substantially equals atmospheric pressure; and disconnecting and removing from the refrigeration system at least a portion of the first and second pump units.

12. The method as defined by claim 11 wherein prior to the step of disconnecting a portion of said pump units, at least one of said pump unit-s is vented to the atmosphere to permit the liquid level therein to fall below the level of that portion of the unit to be removed.

-13. A method of removing a pump motor means from an absorption refrigeration system of the character having an absorber and evaporator normally maintained at subatmospheric pressure and normally at least partially filled with absorbent and refrigerant liquids having first 'and second densities respectively, a first fluid circuit connecting the lower portion of the absorber to the upper portion thereof and having a segment extending below the absorber, a first pump disposed in the first fluid circuit below the absorber for pumping absorbent liquid from the absorber, a second fluid circuit connecting the lower portion of the evaporator to the upper portion thereof and having a segment extending below the evaporator, a second pump disposed in the second fluid circuit below the evaporator for pumping refrigerant liquid from the evaporator, a motor means drivingly connected to each of the first and second pumps and having at least a portion thereof in fluid communication with at least one of the absorbent and refrigerant liquids circulated respectively by the first and second pumps, a first liquid trap disposed in the first fluid circuit below the absorber upstream of the first pump, and a second liquid trap disposed in the second fluid circuit below the evaporator upstream of the second pump, comprising the steps of: providing said absorber and evaporator with a source of inert gas; charging said absorber and evaporator with sufficient gas from said source that the sum of the total gas pressure within said absorber and the hydrostatic pressure, in said first fluid circuit at a level below said absorber upstream of said first pump and above said first trap, substantially equals atmospheric pressure and passing suflicient quantity of liquid of one density from one of said first and second fluid circuits into the liquid of the other density in the other of said first and second fluid circuits that the sum of the total gas pressure within said evaporator and the hydrostatic pressure, in said second fluid circuit at a level below said evaporator upstream of said second pump and above said second trap, substantially equals atmospheric pressure; and disconnecting and removing said portion of said motor means from said refrigeration system.

14. The method as defined by claim 13 wherein prior to the step of disconnecting said portion of said motor means, at least one of said first and second pumps is vented to the atmosphere to permit the liquid level therein to fall below the level of the motor means of said one pump.

15. A method of removing a pump means from an absorption refrigeration system of the character having an absorber and evaporator normally maintained at subatmospheric pressure and normally at least partially filled with absorbent and refrigerant liquids having first and second densities respectively, a first fluid circuit connecting the lower portion of the absorber to the upper portion thereof and having a segment extending below the absorber, a first pump disposed in the first fluid circuit below the absorber for pumping absorbent liquid from the absorber, a second fluid circuit connecting the lower portion of the evaporator to the upper portion thereof and having a segment extending below the evaporator, a second pump disposed in the second fluid circuit below the evaporator for pumping refrigerant liquid from the evaporator, a first liquid trap disposed in the first fluid circuit below the absorber upstream of the inlet of the first pump,

' and a second liquid trap disposed in the second fluid circuit below the evaporator upstream of the inlet of the second pump, comprising the steps of: providing said absorber and evaporator with a source of inert gas; chargingsaid absorber and evaporator with suflicient gas from said source that the sum of the total gas pressure within said absorber and the hydrostatic pressure, in said first fluid circuit at a level below the absorber upstream of the inlet of said first pump and above said first trap, substantially equals atmospheric pressure and passing sufficient quantity of liquid of one density from one of said first and second fluid circuits into the liquid of the other density in the order of said first and second fluid circuits that the sum of the total gas pressure within said evaporator and the hydrostatic pressure, in said second fluid circuit at a level below the evaporator upstream of the inlet of said second pump and above said second trap, substantially equals atmospheric pressure; and disconnecting and removing at least a portion of said first and second pumps from said refrigeration system.

16. The method as defined by claim 15 wherein prior to the step of disconnecting said portion of said first and second pumps, at least one of said first and second pumps is vented to the atmosphere to permit the liquid level therein to fall below the level of the inlet of said one pump.

17. An absorption refrigeration machine comprising in combination an evaporator; an absorber; fluid passage means connecting the upper portion of said evaporator to the upper portion of said absorber; a first fluid circuit means connecting the lower portion of the evaporator to the upper portion of the evaporator; a first pump unit disposed in said first fluid circuit means below said evaporator and having a portion to be removed; a second fluid circuit means connecting the lower portion of the absorber to the upper portion of the absorber; a second pump unit disposed in said second fluid circuit means below said absorber and having a portion to be removed; means for normally maintaining a subatmospheric pressure in said evaporator and absorber; and means for removing from said refrigeration machine at least a portion of each of said first and second pump units including means for supplying an inert gas to said evaporator and absorber, a first liquid trap in said first fluid circuit means disposed below the evaporator upstream of that portion of said first pump unit to be removed, a second liquid trap in said second fluid circuit means disposed below the absorber upstream of that portion of said second pump unit to be removed, and means adapted for connecting said first and second fluid circuit means adjacent said first and second liquid traps for conducting liquid between said first and second fluid circuit means.

18. The apparatus as defined by claim 17 wherein means is provided for venting at least one of said pump units.

'19 An absorption refrigeration machine comprising in combination an evaporator, an absorber, fluid passage means for conducting vapor from said evaporator to said absorber, a refrigerant circuit means for conducting liquid refrigerant from the lower portion of said evaporator to the upper portion of said evaporator, a refrigerant pump dlsposed in said refrigerant circuit means below said evaporator, an absorbent solution circuit means for conducting absorbent solution from the lower portion of said absorber to the upper portion of said absorber, an absorbent solution pump disposed in said absorbent solution circuit means below said absorber, a liquid trap disposed 111 series with and upstream of one of said pumps, said References Cited by the Examiner UNITED STATES PATENTS Leonard 62125 Kaufman et a1 62-141 Aronson 62487 X Phillips et a1. 62-488 X LLOYD L. KING, Primary Examiner. 

1. A METHOD OF REMOVING A PUMP MOTOR FROM AN ABSORPTION REFRIGERATION SYSTEM OF THE CHARACTER HAVING A CLOSED VESSEL NORMALLY MAINTAINED AT SUBATMOSPHERIC PRESSURE AND NORMALLY PARTIALLY FILLED WITH A LIQUID, A FLUID CIRCUIT MEANS FOR CONDUCTING LIQUID FROM A PORTION OF THE VESSEL TO A HIGHER PORTION OF THE VESSEL, A PUMP DISPOSED IN THE FLUID CIRCUIT MEANS AT A LEVEL BELOW THE VESSEL, AND A MOTOR DRIVINGLY COUPLED TO THE PUMP AND HAVING AT LEAST A PORTION THEREOF IN FLUID COMMUNICATION WITH THE LIQUID IN THE FLUID CIRCUIT MEANS, COMPRISING THE STEPS OF: PROVIDING SAID FLUID CIRCUIT MEANS WITH A LIQUID TRAP MEANS DISPOSED BELOW SAID VESSEL; PROVIDING SAID VESSEL WITH A SOURCE OF INERT GAS; CHARGING SAID VESSEL WITH SUFFICIENT GAS FROM SAID SOURCE THAT THE SUM OF THE TOTAL GAS PRESSURE WITHIN SAID VESSEL AND THE HYDROSTATIC PRESSURE, IN SAID FLUID CIRCUIT MEANS AT A LEVEL BELOW SAID VESSEL ABOVE SAID TRAP, SUBSTANTIALLY EQUALS ATMOSPHERIC PRESSURE AND DISCONNECTING AND REMOVING SAID PORTION OF SAID MOTOR FROM SAID REFRIGERATION SYSTEM. 